As portable devices are becoming more common, headsets are proliferating. Headsets include the Bluetooth headsets or plug-in headsets often used with mobile phones, headphones used with music players or other listening devices. Headsets may also be used with stationary devices such as landline telephones, computers, stereos, etc.
While many older headsets are unpowered devices, simply using wires to lead the sound to the user's ears, newer headsets are powered, and often include some processing power. In particular, headsets that have wireless connectivity are battery powered. Some wired headsets also are powered to provide noise cancellation or other features.